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Men react to flu vaccination differently than women
Women and men often show clear differences in the immune response to vaccinations and infections. A team of researchers from US and French scientists has now analyzed these gender-specific differences in more detail using flu vaccine and identified testosterone as the probable cause of the deviating immune reactions.
To analyze the gender-specific immune response to a flu immunization, the scientists led by Mark Davis from Stanford University in California and Boris P. Hejblum from the University of Bordeaux subjected 53 vaccinated women and 34 vaccinated men to a thorough examination. "A large number of components of the immune system, including serum cytokines and chemokines, blood cell volume and cellular responses to various stimuli" were recorded, the researchers write in the journal "Proceedings of the National Academy od Sciences" (PNAS). Davis, Hejblum and colleagues also took into account the genetic disposition of the participants. In the course of their investigations, the scientists identified a "group of genes in lipid metabolism" (fat metabolism) that "apparently is related to the reduced immune response in men and whose activity is influenced by testosterone", as described in the study report.
Women show a stronger immune response According to the researchers, "it was already known from various previous studies that men had a weaker immune response than women after both vaccinations and infections". However, the mechanisms underlying these differences have largely remained unclear, reports Davis and Hejblum. Using the immune response to a “trivalent inactivated seasonal influenza vaccine”, the researchers have now identified possible causes for the gender-specific differences in the immune response. They initially found that women developed significantly more antibodies than men and that "the expression of inflammation-promoting cytokines in the serum of women compared to men regardless of age" was significantly higher. The researchers were also able to identify a cluster of genes that are involved in fat metabolism and are apparently related to the immune response to the flu vaccine. According to Davis, Hejblum and colleagues, his activity was closely correlated with the level of testosterone in the blood. "Men with elevated serum testosterone levels and the corresponding gene signatures showed the lowest antibody responses," the researchers report.
Testosterone causes a reduced immune response in men The results of the current study show "a close connection between the immune response, the sex hormones (androgens) and the genes that are involved in lipid metabolism," report Davis and Hejblum. In her view, "there is some evidence that testosterone is the major cause of the different immune responses in men and women". Evolution may explain the weakening effect of testosterone on the immune response by the fact that men suffered more injuries while hunting and an overreaction of the immune system should be avoided here. With regard to the recommendations on flu vaccination made by the Robert Koch Institute (RKI) in Germany, the current findings have little meaning, but the question arises whether in the future vaccinations should not be differentiated between men and women.
Do men actually suffer more? The study results also provide an indication of why men feel harmless infections and often suffer significantly more and longer than women. Because your immune system can only defend itself insufficiently due to the high testosterone level. According to current knowledge, fluctuations in the hormone level could also have a lasting effect on the immune defense, but further studies are required here to clarify the connections. (fp)